This invention relates to the cutting and scoring of cardboard and paper or other materials, and more particularly, to a coated plate for use in uniformly positioning a cutting knife or scoring tool with respect to a sheet to be cut into a blank.
For instance in the manufacture of three-dimensional cardboard containers, such as for medications and the like, a two-dimensional cardboard sheet is cut and scored to form a "blank". The blank is folded along various score and cut lines to achieve the desired three-dimensional or box-like shape.
The sheet is cut and scored by feeding the sheet into a press which usually carries a movable lower platen and a stationary upper platen to which a die-and-knife assembly is secured. The die which has the blank outline therein is usually secured to the movable platen but may be secured to the stationary platen. The cutting knife is positioned in slots or openings in the die which are specifically cut therein to hold the cutting knives or other similar tools. The press is closed to cut and score the sheet and then opened to remove the cut blank.
The knives and scoring tools (elongated band-like elements that have an exposed sharp or working edge) extend through the die and abut at their back end against the platen. The platen surface, behind the die, may be irregularly shaped, and it is usually necessary to "shim" the knife by inserting a paper shim between the knife and platen so that the cutting edges of the knife lie in a plane. This is usually tested by cutting a sample and determining if the edges have cut uniformly. The shimming operation has been expensive, time-consuming, an art rather than a science, and since the paper may change or be unstable with the number of impressions, the alignment may also change.
One approach to solving these problems has been to provide a knife with a softened back edge which is intended to rest against the hard platen and in a sense self-adjust or conform to the platen irregularities. One such system is disclosed in U.S. Pat. No. 4,256,026. However, this system still requires knife positioning adjustment to assure even cuts, it has too limited a range of automatic adjustment and it subjects the exposed machine parts to damage.
It is therefore the object of this invention to provide an efficient knife or tool adjustment for use in cardboard paper or other material cutting and scoring.
This and other objects of this invention shall become apparent from the following description and appended claims.